In our climate, the aluminum heater cores with plastic end tanks will fail suddenly at the 20+ year mark under normal cooling system pressure. The original in my aunt's STS failed after 23 years (end of summer), but clean-up was easy thanks to the deep floormats.

Dang.Overheating on the highway points to a bad radiator, waterpump or thermostat. Since I think you did the pump recently I guess it's down to the others. The less common one would be clogged coolant passages. The only one of my cars that hasn't had a radiator that I've had to put in is Peach. Chester and the Wildcat both had overheating on the highway issues. Rocky sprung a leak.

As for Chester,I hooked up the battery tender and then sat in front of it on a folding chair while the girls rode their bikes. Nice 8degC weather. I did the spring overhaul on both bikes (brake adjustment, seat adjustment, tire pump, chain lube) and needed to replace the pedal on 1 bike. Swapped over kick-stand and streamers (a must on Kayda's bikes) from an older bike.Spring is near!

I had another look today. There is coolant in the overflow tank and the passenger side floor mat doesnt have much coolant in it. I was wondering if it might be a bad thermostat. It was running cool and never got above 91C.

It's at Minuite muffler right now. They said they can get it in later today.

GJ

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Some people are like a Slinky. Not really good for anything, but you still can't help but smile when you shove them down the stairs.

Perhaps the heater core being the weak link let go when the engine got hot. The core issue may be a bad thermostat restricting flow. Even in the milder weather, a slightly restricted rad shouldn't restrict flow enough for the engine to get that hot. If it were, it would have revealed itself on the trip to Toronto.

While investigating odd cooling system behaviour, the first thing to check is the purge line that runs from the thermostat area to the surge tank. There have been reports of debris plugging the feed orifice or even somewhere inside the line itself. The orifice is located at a local high point and loss of flow may affect the performance of the inlet thermostat.

Interesting. That was an issue in the old Detroit Series 55 powered buses we had. The vent line from the surge tank to the thermostat housing would plug leading to hot running conditions, particularly if any cooling system service was performed. It was routine to check that line anytime the system was drained.

I think it's safe to say that the worst of this winter is gone bye-bye but I'm not going to hold my breath.I'm itching to get my Eldorado uncovered so I can get it ready for summer. I have a bunch things thathave to be taken care of so I can use it. I have to get that passenger side exhaust manifold leak fixed.We don't know if it's the manifold gasket that leaks or if the manifold itself is cracked. You can't seeanything because all the pollution equipment is in the way. Can cast iron be welded so it's strong enoughto not come apart from all that exhaust heat or should I try to find another manifold ?I have to get the bumpers off so I can replace some of the right side filler pieces and the vinyl roof needs to be re-colouredI'm not sure if I should have a tune up done. The last time one was done was 10 years ago but I haven'tput more than 25,000 - 30,000 miles on it since then so I don't know if it really needs it.

My daily driver (06 DTS) has lost the seat memory a couple of times in the last 2 months. It has a little over 172k. The battery is about 2 years old and according to the reading on my dash is charging in the 14.2-14.3 range consistently. No problems starting.

Back in 2012 the driver seat quit. It went to 2 shops (2nd was the Cadillac dealer) and between the 2 shops cost me over 1,000 to fix.